Two analog interview questions from the website

[bhl777]

Hi everyone, I have some questions regarding two interview analog questions on the website, s anyone able to solve them? Thank you very much!

1. For the following circuit, if the input is a rail-to-rail square wave, plot the wave after the inverter and vo.



2. For the following circuits, Vdd=5v, tell me what are Vo1 and Vo2 when Vin is 5V, 3V, 2.5V and 0V.



THANK YOU VERY MUCH!!!!!!!!!!!!!

 

[keith1200rs]

It may just be me but your images are black with some I/O and power labels.

Keith

 

[bhl777]

Hi Keith, that is my problem! I am sorry and have revised, could you have a look at them now? Thank you!

It may just be me but your images are black with some I/O and power labels.

Keith

 

[keith1200rs]

The first stage of the first circuit is an inverter so the output will be rail to rail. The second stage is a complementary follower so it will not invert and the output will not be rail to rail - it will only get within Vth of the rails.

Keith

 

[keith1200rs]

For the second circuit, Vo1 will follow the input, but Vth below it. Vo2 is a common source amplifier so will invert. It is difficult to be precise about the characteristics of the circuit as it has no output load. That is also true of Vo1.

Keith